Post-arc current measurement based on current transfer characteristic

Abstract

The paper proposes a novel post-arc current measuring equipment (PACME), which is composed of vacuum switch, transfer resistance, protective gap and high-precision current sensor. The principle of the measurement is based on current transfer characteristic between the vacuum switch and transfer resistance. The current-transfer model of the post-arc current measurement is established to gain the characteristic of vacuum arc conductance and the completion time of current transfer influenced by the transfer resistance, current of main circuit and the contacts opening time. The vacuum arc of PACME extinguished just before the main current approach zero while the main current is completely transferred to the transfer resistance. According to the simulation result, the PACME is designed, especially; the transfer resistance is non inductive and over current protection. The post-arc current of vacuum switch with axial magnetic field (AMF) and transverse magnetic field (TMF) contacts was measured in synthetic short-circuit test. The measuring result of post-arc current is accurate and small interference, which satisfied the post-arc current measurement of vacuum circuit breakers.